TX 763 
.884 
Copy 1 






A HANDY MANUAL OF UP-TO-DATE 
MONEY-SAVING SUGGESTIONS AND 
FORM-SHEETS FOR SMALL AND LARGE 
BAKERIES, THE RESULT OF YEARS OF 
STUDY AND PRACTICAL EXPERIMENTS 



PART 5 
Heat, Combustion, Fuel, Ovens, 



BY 

EMIL BRAUN 

(Expert and Consulting Baker) 

Author of "Perfection in Baking," 
"The Baker's Book," Vols. I. and II. 



Published By 

EMIL BRAUN 

Cincinnati, Ohio 

1911 



ip%" 



*! 



Copyright, 1911 

by 

EMIL BRAUN 

Cincinnati, O. 



©CIA 



283227 






PART 5. 

Heat, Combustion, Fuel, Ovens. 

— 

HEAT. 

The introduction of machinery and patent bake- 
ovens necessarily demands of the up-to-date baker a 
more or less technical education. The regulation of 
the temperature of water, sponge and dough, as well 
as the regulation of heat in bake-shops and the ovens, 
must be studied, and the principles governing them 
properly applied. 

The heat in a bake-oven can and should be kept 
under control just as the engineer has perfect control 
over his engine or boiler. A pyrometer or thermo- 
meter should be attached to every bake-oven, whether 
made of brick or iron; indirectly (flue-heated) or in- 
side (direct) fired. There are three different scales 
of heat measure ; the Reaumur, Celsius or Centi- 
grade and the Fahrenheit. To abbreviate these names 
on pyrometer or thermometer, the following letters 
are used: R. (Reaumur), C. (Celsius), F. (Fahren- 
heit). The freezing point on the R. and C. is marked 
at zero, 0, while on the F., it is 32 degrees above zero. 
The respective boiling points are marked at R. 80 de- 
grees, C. 100 degrees, F. 212 degrees. In R. and C, 
reading the number of degrees below zero are marked 
"Cold,'' or "Minus" ( — ) degrees. Those above are 
marked "Heat," or "Plus" ( + ) degrees. By this you 
can readily understand how important it is to men- 
tion the system of "Scale" used when speaking of 
temperature. 

To transform degrees of Fahrenheit into Reau- 
mur, you deduct 32 from the F. degrees ; multiply 
the remaining number by 4, and then divide by 9. 



2 Part 5 

For example: 77 degrees F. are equal to 20 R; de- 
duct 32 from 77, equals 45; multiply with 4, equals 
180; divide by 9, equals 20. 

To transform Fahrenheit into Celsius, deduct 
32 ; multiply by 5, and divide by 9. 

To transform Celsius into Reaumur, multiply by 
4, and divide by 5. To transform Celsius into Fahren- 
heit, take the number of C. degrees 1 4-5 times, and 
add 32. 

To transform R. degrees into C, take the num- 
ber of R. l}i times. R. degrees are transformed 
into F. ? by taking the number of R. degrees 2% times 
and add 32. 

Mercury has been adapted as the standard for 
use in thermometers, due to the regular and never- 
varying way in which it expands or contracts under 
normal conditions. The column of mercury in the 
tube of a thermometer seems to be round, and about 
one-sixteenth of an inch in diameter. As a matter of 
fact, it is flat, and a good deal finer than a single 
hair. Mercury does not expand to any great extent 
so it is imperative that we confine it in as small a 
space as possible. It is the magnifying effect of the 
glass that enables us to see it so plain. Spirits of wine, 
is sometimes used, with coloring matter added, but -it 
is not perfectly accurate. 

Up till a few years ago, Mercury Thermometers 
for bake-ovens were not extensively used, owing to 
their frail construction and liability to breakage as well 
as constant separation of the mercury column. Mod- 
ern manufacturing methods and new invention along 
this line have overcome these defects. There are now 
on the market two distinct styles of heat records. 
They are the Angle Thermometer and the Improved 
Pyrometer. In classing the heat indicators on the 
market to-day in two styles, I reserved the "Electric 
Pyrometer" for a class in which it stands alone. With 
this instrument, the height of achievement has cer- 



Part 5 3 

tainly been reached. In most shops, while the oven- 
man is responsible for the appearance of goods coming 
from the oven, it is the foreman in charge who gets 
the blame for things going wrong. Think of the 
saving of time and worry for the foreman or superin- 
tendent who has such diverse things to keep his mind 
on, to be able at a moment's notice to stand at one 
end of a chain of ovens or in his office and see the 
temperature of every oven in the shop by simply 
throwing an electric switch. Could we wish for any- 
thing more simple and satisfactory? The movements 
and all parts subject to heat on these as well as 
the modern thermometers and pyrometers now on the 
market are made of non-corrosive material. They 
are all very sensitive, and the indicator shows instantly 
the slightest variation in temperature. The proper 
degree of heat for baking and handling of the above 
instruments will be more thoroughly mentioned under 
"Ovens and Firing. ,, It appears that this part of the 
shop system has been grossly neglected in most bak- 
eries, both large and small. If the firing of different 
styles of ovens is properly understood, a more uni- 
form heat is acquired and a great saving in fuel is 
the result. Very few bakers have paid any attention 
even to the first principles of combustion and heat 
units. However, before we go into details of correct 
firing methods and kinds of fuel, a few facts on the 
principles of combustion will be necessary. 

COMBUSTION. 

Chemists classify all known substances either as 
elements, compounds or mixtures. We will deal only 
with the elements and compounds. Compounds are 
those substances which can by chemical action or by 
action of physical energy (heat or electricity) be di- 
vided into two or more simpler substances. These 
substances which cannot by any known means be 
further split up are called elements. The principal 



4 Part 5 

elements we have to deal with in the combustion of 
fuel are: 

Carbon C. 

Hydrogen H. 

Oxygen O. 

Sulphur S. 

In referring to these elements, it is customary to 
use the symbol or abbreviation which is usually the 
first letter. Thus, C stands for Carbon, and O for 
Oxygen. 

Popularly, combustion means fire or burning. Ex- 
clude air from a fire, and the fire goes out. Oxygen 
is therefore necessary for combustion. Science has 
proved that oxygen has a great attraction for carbon, 
therefore, when these two elements are exposed, they 
rush together with great rapidity and force, and the 
chemical action is accompanied by light and heat. In 
combining in this way, they form an invisible gas, 
called carbon dioxide. The chemical symbol of this 
is CO2 . From this we plainly see that for every part 
of C or carbon present, we must have two parts of O, 
or oxygen. If we do not have these proportions pres- 
ent, a different gas is formed, producing through the 
chemical action, a larger or smaller amount of chemical 
energy, or heat. For instance, cut off the air supply, 
until you have but one part of O or oxygen for each 
part of C, or carbon, and these two uniting, form the 
gas Carbon Monoxide, the chemical symbol of which, is 
CO. When this occurs, that is, when less air is sup- 
plied, the combustion is said to be imperfect, and the 
carbon burns to CO instead of CO2. The quantities 
of heat produced by the complete combustion of carbon 
in our fuel, is found by experiment to be as follows : 

Carbon burned to CO2 generates 8080 calories, 
or 14500 B. T. U. 

Carbon burned to CO generates 2473 calories, or 
4452 B. T. U. 

By this you see we lose 5607 calories or 10,000 
B. T. U., if the supply of air is not sufficient to burn it 



Part 5 5 

from CO to CO 2. Calories is the standard name in 
referring to the table of Heat Units. A calorie of heat 
is the amount of heat required to raise the temperature 
of one gram of water, from degrees to one degree, 
Centigrade. This is called the Gramme-Calorie or lesser 
calorie. For measuring larger quantities of heat, just 
the calorie is used. This is the amount of heat neces- 
sary to raise one kilogram of water, through one degree 
of Centigrade. The Gramme-Calorie is 1-1,000 part 
of the Calorie above mentioned. 

There is another system of heat units used among 
engineers that depends entirely on British standards of 
weight and temperature. This is called the British 
Thermal Unit, and is abbreviated B. T. U. One B. 
T. U. represents the amount of heat required to raise 
one pound of water through one degree F. 

To transform Calorie Units (metric system) into 
British Thermal Units (Fahrenheit degrees) multiply 
the former by 9 and divide by 5. 

Usually the quantity of air admitted to the furnace, 
is from 50 to 100 per cent more than is necessary for 
the complete combustion of the fuel. This extra quan- 
tity of air enters the furnace at a temperature of from 
60 to 70 degrees and escapes up the chimney at a 
temperature of from 400 to 600 degrees. A large 
quantity of heat is thus wasted and the temperature 
of the fire lowered. So you see that by being careful 
not to get too much draft, you overcome the loss of 
heat the same as by being careful that you have enough. 
Following are a few conditions existing in our fuels 
that aid or retard complete economical combustion, 
and they should be understood by all bakers. 

The conditions necessary to consume the gases 
generated are the same as for the burning of the car- 
bon, that is, a sufficient supply of air, allowing it a 
chance to mix with the gases at a high temperature 
in the furnace box. 

Be sure that your fuel is not wet. The moisture 
of the fuel must be evaporated at the expense of the 



G 



Part 5 



heat produced by combustion. This moisture enters 
the furnace at the prevailing outside temperature, say 
70 degrees, and passes up the chimney in the form of 
vapor, at 400 degrees or more. In producing this 
rise in temperature, thousands of heat units will be 
lost daily. Therefore, always keep your fuel under 
cover as far as can be helped, and never expose it to 



rain. 



Oxygen and hydrogen are found in fuel in com- 
bination in the form of moisture. This is one reason 
for using fuels containing as small a percentage as 
possible of these two elements. Although black smoke 
contains quantities of small particles of unburned car- 
bon, the heat loss is not as great as we might imagine. 
This is more thoroughly treated under the heading of 
Firing. 

Now that we have a little better knowledge as to 
how our fuel is consumed, we will discuss the various 
kinds of fuel. 

Comparative Table of Total Heat Evolved During Combustion. 



Combustibles 
1 Lb. Weight 



C to CO 

C to CO 
Average Coal 

Coke 

Wood 



Weight of 
Oxygen 
Consumed 
per Pound 

of 
Combustible 



Qyantity of Air 

per Pound 
of Combustibles. 



2.66 
1.33 
2.46 
2.50 
1.40 



Lb. 



11.60 

5.80 

10.70 

10.90 

6.10 



Air Cubic 
Ft. at 60° F. 



152 

76 

140 

143 

80 



Total Heat 

per Pound 

of 

Combustible 

B. T. U. 



14500 

4452 

14133 

13550 

7792 



Part 5 



Chemical Composition of Combustibles. 

PECLET (Authority). 





Carbon, 


Hydro- 
gen 


Oxygen 


Nitrogen 

and 
Sulphur 


Water 


Ash 


Total 


Coal 

(Average) 


.804 
.850 
.510 

.408 
.930 


.0519 


.0787 


.0246 




.0408 

.150 

.020 

.016 
.070 


1.000 


Coke 




1 000 


Wood (Dry) 


.023 
.042 


.417 
.334 






1.000 


Wood 

(Ordinary) 

Charcoal 

(Wood) 




.200 


1.000 
1 000 















FUEL. 

Fuel is now such an expensive commodity that the 
economic ways in which it can be used, its quality, 
and power to generate heat, become subjects of great 
importance, wherever it is used in large quantities. 

Fuel, as the word is ordinarily used, means all sub- 
stances that burn in the air and produce heat. The 
fuels most commonly used are generally of an organic 
or vegetable origin. This includes all kinds of coal, 
peat, wood, coke, charcoal, as well as combustible gase. c 
and liquid fuels. All fuels consist of more or less car- 
bon, an element necessary for producing heat. But 
hydrogen, oxygen, nitrogen, sulphur and ash are all 
substances found in the above list of fuels, and must 
be considered, as the quantities in which they are 
present influences the value of any fuel as a heat pro- 
ducer. The number of heat units they produce ranges 
between wide limits, and vary according to the chemi- 
cal composition. The more organic oxygen present in 



8 Part 5 

a fuel, the less heat produced, owing to its being in 
combination with other elements. Sulphur is also an 
undesirable element in fuel, as it does considerable 
damage by corroding the grate bars, flues, chimneys 
and oven fixtures. The more ash a fuel contains, also 
lowers its value for economic purposes, as less heat is 
produced and much time is lost cleaning fires and 
digging out clinkers. 

Many of the large manufacturing concerns and 
institutions employing chemists, make a practice of de- 
termining the chemical composition of their coal. By 
doing this, they are enabled to buy only those fuels, 
coal or coke, having the largest percentage of heat- 
producing elements. This detail work in connection 
with fuel has not, to the author's knowledge, been 
adapted by any of our large bakers. 

I will give a few practical pointers on the compo- 
sition and action during combustion of various fuels, 
that may be of interest and value to the baking in- 
dustry and the manufacturers of bake-ovens. Opin- 
ions about the most economical fuel for bakers' ovens 
differ, and local prices of material must be considered 
in the selection of the fuel. 



COAL. 

Coal is divided into four different varieties, the 
market price of which vary considerable. They are 
mentioned as follows : 

1. Anthracite coal, which contains about 92 or 
more per cent of carbon. 

2. Semi-anthracite coal, over 85 up to 93 per 
cent of carbon. 

3. Semi-bituminous coal, which contains over 70 
to 87 per cent of carbon. 

4. Bituminous coal, which contains from to 
75 per cent of carbon. 



Part 5 9 

ANTHRACITE COAL. 

Does not ignite so quickly and requires a stronger 
draft to burn it. It is quite hard and shiny; burning 
with almost no smoke, gives it the preference over other 
coal in bakeries. 

This coal is sold under different names, accord- 
ing to size into which the lumps are broken. They 
are named in regard to the dimensions of the screens 
over and through which the lumps of coal will pass, 
for instance : 

PEA passes over y 2 -'mch mesh and through 1-inch 
square mesh. 

CHESTNUT passes over ^-inch mesh and 
through \y 2 -inch square mesh. 

STOVE passes over 1^-inch mesh, and through 
2-inch square mesh. 

EGG passes over 2-inch mesh, and through 3-inch 
square mesh. 

Another advantage in using anthracite coal, is the 
fact, that its available heating power is practically 
constant. The semi-bituminous coals and all good 
caking, soft coals yield just about the same quantities 
of available heating power as does the best anthracite 
coal, but require more attention and raking and con- 
sequently the fire and heat is not as constant and uni- 
form as if the former coal is used. 

Anthracite is a non-caking coal. As stated, it 
contains more carbon than any other coal and the least 
amount of volatile matter (hydrocarbons) from one to 
ten per cent. The best anthracite coal is mined in the 
northeastern part of Pennsylvania, in the Lehigh Val- 
ley, Susquehanna, Shamokin and Lackawanna Dis- 
tricts. Occasionally, you get some anthracite coal 
which is flinty and hard as stone. It is almost im- 
possible to ignite it; just glows like stone and the 
pieces frequently fly all apart in the furnace with a 
crackling noise like a gun explosion. Such coal is 



10 Part 5 

called Graphitic Anthracite, contains from 1 to 2 per 
cent of gaseous matter and as a fuel is almost worth- 
less. Graphitic Anthracite is found more frequently 
in the New England coal fields, especially in the Rhode 
Island Basin. 

SEMI-ANTHRACITE coal has about the same 
composition as the anthracite, but, is not as hard and 
burns more quickly ; it crumbles readily and is not as 
clean, but burns with little smoke. Contains from 8 
to 12 per cent, of volatile hydro-carbons. 

BITUMINOUS COAL. 

SEMI-BITUMINOUS coal containing from 12 
to 25 per cent, of volatile hydro-carbons is easily ig- 
nited, burns freely with little or no smoke and is used 
extensively for heating steam boilers. This coal forms 
a hollow fire. 

BITUMINOUS COAL contains the most volatile 
hydro-carbon, varying from 20 to over 75 per cent. 
The nature and composition of this coal varies more 
than any other kind of fuel, therefore they are divided 
into three distinct classes: 

1. Caking Coal are those which swell and fuse 
together, forming a solid, spongy mass when burned 
in the furnace or grate. Therefore the fire must be 
frequently broken down with a slice bar and cleared 
from the grate in order to admit the air to pass 
through. 

2. Free Burning or Non-Caking Coal is so called, 
because it does not cake together as the above men- 
tioned varieties. 

3. Cannel or Gaseous Coal is very rich in vola- 
tile matter or hydro-carbons and therefore preferred 
for making gas. 

SLACK is the name given to the dust or left overs 
from any soft coal after they are screened. 

LIGNITE or BROWN COAL is the connecting 
link between Peat and Bituminous coal, the color varies 
from brown to black, absorbs moisture very rapidly 



Part 5 11 

when exposed to the weather, which causes the lumps 
to break up and crumble quite readily. It burns quite 
easy and freely with a yellow flame and emits a tar- 
like disagreeable odor. However, its heating power 
is very low and it leaves considerable ash; is classed 
as a non-caking coal. 

PEAT is the first product resulting from decayed 
vegetable matter, partly carbonized and being found in 
marshes and swamps ; it generally is spongy and satu- 
rated with moisture, containing on the surface as high 
as 80 per cent water ; deeper down where it is more 
de-composed, it is also more solid. Before being fit 
for transport or burning, it must be dried out, being 
cut or pressed into brighettes. 

HARD COAL VERSUS SOFT COAL. 

When caking coals are burned, they fuse at com- 
paratively low temperatures, forming a crust over the 
top of the fire which prevents the immediate escape of 
the volatile gases that comprise from 40 to 50 per 
cent of the fuel's heating power. 

These gases are then driven to the side of the 
fire-pot where they unite with the rising oxygen and, 
igniting at that point, are converted into volatile heat- 
ing power. 

When free burning coals are used, they disinte- 
grate at comparatively low temperatures and some of 
the hydro-carbon gases escape without coming in con- 
tact with the necessary oxygen for ignition. 

It makes quite a difference whether the coal is dry 
or wet. If it is wet, a large percentage of heat is 
necessary to bring up the temperature of the wet fuel 
to 212° first, in order to turn the water (dampness) 
into steam, and as a large percentage of this steam 
passes through the flues and chimney, that amount of 
heat is lost for heating purpose. As mentioned before, 
to raise the heat of one part (say one pound) of water 
one degree Fahrenheit it takes one Heat Unit. There- 
fore, if you pour one pound (one pint) of water at 



12 Part 5 

60 degrees F. over the coal, it takes 152 Heat Units 
(B. T. U.) to raise the water from 60 to 212 degrees 
F. or to the boiling point and as it takes about 970 
Heat Units (B. T. U.) to evaporate or turn this pint 
of water into steam, you need altogether 152+970= 
1122 Heat Units (B. T. U.) This same example 
worked out in Calories would read like this : For one 
Kilogram (one liter) water at 15 degrees Centigrade 
or Celsius (60 degrees F.) it takes 85 Calories to raise 
this pint of water from 15 C. to 100 C. or the boiling 
point, and as about 540 Calories are required to evap- 
orate or turn all the water into steam, you need alto- 
gether 85+540=625 Calories, which equals the 1122 
British Thermal Units on Fahrenheit bases. 

This example shows very plain that large quan- 
tities of heat are lost when damp or wet fuel is used. 

COKE. 

Is the residue left from certain kinds of Bitumin- 
ous coal, when burned or heated with almost the en- 
tire exclusion of air and all its volatile matter driven 
off, leaving practically only carbon and a little ash. 
(see table.) It does not resemble the original coal 
at all ; is hard, rough and honey-combed, and has a 
metallic ring, being much lighter than coal. Coke 
burns with almost no flame when combustion is com- 
plete. 

GAS HOUSE COKE is a by product from the 
manufacture of illuminating or artificial gas and mostly 
consumed locally. 

FURNACE COKE used to be made similar to 
charcoal in piles or mounds, but the demand having 
steadily increased, large Kilns and Coke Ovens of 
brick or stone have been erected for its manufacture. 
The most extensive coke centers are located around 
Pittsburg in the Connelsville district and the Alle- 
ghaney Mountain sides. West Virginia also produces 
considerable coke in the New River and Kanawha 
districts. Furnace coke is classed and its price fixed 



Part 5 13 

according to the time it has been in the oven. (Car- 
bonizing.) The standard kinds are known as 48 and 
72 hour coke, the latter giving the highest number of 
Heat Units. Although the price of the 72 hour coke 
is from 50 to 75 cents per ton higher, it is the most 
economical, very light in weight, dry and uniform 
in size. Good Connel'sville coke analizes as follows : 

Carbon 88.00 to 89.00 per cent 

Ash 9.50 to 11.00 per cent 

Volatile Moisture 1.00 to 1.50 per cent 

Sulphur 0.75 to 0.90 per cent 

GAS 

PRODUCER or ILLUMINATING GAS is dis- 
tilled from coal. On account of its high price it is used 
very little for heating bake ovens. Its heating value 
is estimated at about 155 B. T. U. per cubic foot. 

NATURAL GAS. In sections where a plentiful 
supply of natural gas has been discovered, it is used 
very extensively, and to-day is supplied from central 
stations to cities hundreds of miles away. The only 
trouble with natural gas is the inconsistency of pres- 
sure and in some localities the flow has given out en- 
tirely. Natural gas concerns claim that on an average, 
20,000 to 23,000 feet of this gas has the heating value 
of one ton of coal. The principal constituent is Marsh 
Gas (Methane) C. LU. The complete or proper com- 
bustion of natural gas is a problem which kept many 
scientists and engineers busy and experimenting ever 
since the introduction of natural gas for heating pur- 
poses. 

The combustion of natural gas is a very difficult 
problem to solve. To be able to use this ideal fuel 
successfully, - both from a commercial and financial 
standpoint^ a few fundamental principles must be 
observed. 

1. The proper amount of gas and oxygen must 
be brought in contact with each other. 

2. After being brought together, they must be 
thoroughly mixed before reaching the point of ignition. 



14 Part 5 

3. Combustion must take place before they have 
a chance to separate again, which they will do soon 
after being mixed. 

The supply of proper amount of air must be 
watched, as a natural gas flame cannot exist unless 
supported by oxygen. Withdraw the air or oxygen 
supply, and the flame will be extinguished, while the 
gas will keep on flowing or escaping. Therefore, care 
must be taken when lighting a gas burner in any inside 
or furnace oven, that the dampers are first opened and 
that there is enough draft to carry away the product 
of combustion, otherwise there will be an explosion. 
It is a peculiarity of gas explosions that they strike 
back; that means through the open oven or furnace 
door. The writer witnessed several accidents as a re- 
sult of such gas explosions, where the men opened the 
valves of the burners before they had the lighted torch 
applied. In bakeovens with direct firing (inside the 
oven chamber) the danger of explosion is still greater. 
But nine times out of ten, the man who lights the fire 
is the cause through his carelessness. The writer al- 
ways cautioned his men to surely first open damper 
and oven door for a minute, to let any possible accu- 
mulation of gas in the oven escape before he puts his 
torch or light near the burners or grate, and only then 
open the gas valves. 

One of my foremen was burned three different 
times through his carelessness. One time the force of 
the explosion striking back through the oven door, 
threw him clear across the shop against the wall, burn- 
ing his chest and face frightfully. 

As there may be a leak somewhere, unnoticed, it 
is the safest way to have an automatic pilot (small 
flame) burning all the time. 

Air and gas may be compared to oil and water, as 
they will not mix unless they are violently agitated, 
and unless combustion takes place promptly after prop- 
er amount of oxygen and the carbon in the gas have 
been agitated, they will separate again and escape with- 



Part 5 15 

out furnishing the desired heat. As stated before, 
complete or perfect combustion requires the union of 
one atom of carbon C. and two atoms of oxygen O 2. 
The gas people claim that they can use nearly 80 per 
cent of air with their gas. 

A natural gas from Pittsburg district shows aver- 
age composition of: 

Marsh gas (C. H 4 . 67.00 per cent 

Hydrogen (H) 22.00 per cent. 

Nitrogen (N) 3.00 per cent. 

Oxygen (O) 0.80 per cent. 

Other gases, ,.. 7.20 per cent. 

There are different styles of gas burners, but they 
do not all answer the purpose of heating bakeovens. 
The writer's experience with different gas burners will 
be explained later on under firing. 

WOOD. 

Is not used as extensively nowadays as a fuel for 
heating bakeovens, as it was before the introduction of 
Patent Flue and Continuous Bakeovens, except for 
kindling the fire. In a general way, one cord of the 
best hard wood is estimated to be equal to one ton of 
coal ; one cord of soft wood is equal to y 2 ton of coal. 
B. & W. Co. give a comparison of 2y 2 lbs. of dry wood 
to one lb. of bituminous coal in heat value. Of course 
these figures are calculated for heating Steam Boilers. 
For heating Bakeovens, I find heating value of wood 
closer to that of coal, especially in inside fired ovens. 
Green wood contains from 30 to 50 per cent of mois- 
ture. When perfectly dry, it contains about 50 per 
cent of carbon. An analysis of Oak has been quoted 
to be composed of 49 per cent carbon, 6 per cent hydro- 
gen, 42 per cent oxygen, a little over 1 per cent ash 
and not quite 1 per cent nitrogen. 

The heating value of wood varies from about 
6,500 B. T. U. to 9,000 B. T. U. or an average of 7,700 
B. T. U. per lb. (see tables, pages 6 and 7, part 5.) 



16 Part 5 

OIL. 

PETROLEUM is being used only in sections 
where coal is scarce and oil plentiful, especially in Cal- 
ifornia, Texas and Wyoming. CRUDE OIL from 
Pennsylvania contains about 85 per cent carbon, 14 
per cent hydrogen, 1.4 per cent oxygen which gives 
a theoretical heating power of about 20,000 B. T. U. 
but there is quite a loss of heat by evaporation, which 
reduces the number of Heat Units considerable. There 
is also danger of explosion. The Standard Oil Co. es- 
timate that 173 gallons of their oil equal one long 
ton (2,240 lbs.) coal, allowing for all savings inci- 
dental to its use. 

COMMERCIAL VALUE OF FUEL. 

The commercial value of a given fuel for a certain 
amount of baking, can only be determined by an ex- 
tended trial, keeping careful records, adding to the 
fuel cost, the cost of firing and removal of ashes. (See 
Oven Record cards). Keeping a record of same 
items under same conditions, but with different fuels, 
it may be found at times, that a low priced fuel can be 
more expensive than the real high priced on account 
of requiring more labor for firing and removing ashes, 
cleaning grate and flues since larger quantities must 
be burned to get the same amount of heat. 

Anthracite Coal (small size) bought at $2.50 per 
ton will furnish about 10,000,000 B. T. Heat Units 
for $1.00. 

Larger sizes like Stove and Ee:g at the price of 
$6.25 per ton furnishes about 4,500^,000 B. T. U. for 
$1.00. 

The heat value of various grades and qualities 
of Bituminous or Soft coal will lie between the above 
figures or average between 4,000,000 to 10,000,000 B. 
T. U. for $1.00. 

Illuminating Gas at $1.00 per 1,000 cubic feet will 
yield only about 500,000 heat units for $1.00. 

Natural Gas if sold for 10 cents per 1,000 cubic 
foot will give about 10,000,000 B. T. U. for $1.00. 



Part 5 17 

Crude Oil selling at 4 cents per gallon will average 
4,000,000 heat units for $1.00. 

Kerosene selling at 10 cents per gallon is equiva- 
lent to 1,200,000 heat units for $1.00. 

Nearly all liquid fuels (distillates) furnish about 
same amount of heat per pound, but vary greatly in 
cost. 

One ton of Anthracite coal averages 25 bushel at 
80 pounds. 

One ton of soft coal averages 40 bushels at 
Go pounds. 

One ton of coke averages 40-50 bushels at 40 
pounds. 

A " long" ton of coal weighs 2240 pounds, but is 
only sold on these bases to dealers or car load buyers ; 
the extra 240 lbs. being figured as allowance for loss 
or shrinkage. 

BAKE OVENS, 

All old time ovens were fired with wood and were 
built on the same principle as the ovens found to this 
day in most smaller bakeries in Europe, especially in 
country districts. These ovens are well filled with dry 
wood and then fired. When all burned out, the ashes 
are removed and the oven chamber swabbed out with a 
wet cloth fastened to a pole. Such ovens are called 
the old "Vienna" Ovens and are used to this day by a 
number of Italian and French bakers in this country, 
even in New York and other large cities. However, 
with the introduction of modern improvements a great 
number of different constructed bakeovens have been 
devised and placed on the market. They may be di- 
vided into different classes, according to their con- 
struction, method of firing or kinds of fuel required : 

1. DIRECT or INSIDE fired ovens. 

2. INDIRECT or FURNACE fired ovens. 

3. CONTINUOUS BAKING or HOT AIR 
CHAMBER ovens. 

4. HOT WATER or STEAM PIPE ovens. 
Then again baker ovens are known irrespective of 



18 Part 5 

the method of firing or kind of fuel used, under differ- 
ent names according to their mechanical construction, 
such as: Portable Ovens, Stationary (Brick) Ovens, 
Rotary, Reel and Drawplate Ovens, and now we have 
even Traveling ovens. 

DIRECT FIRED OVENS.— In this class belongs 
first the old Vienna Oven as above mentioned, fired 
with wood. After the fire has been drawn, the oven 
is allowed to stand off for one half to one hour with 
door and damper tightly closed, to allow the heat to 
equalize through every part of the oven chamber. 
However, after two or three batches are baked, the 
chamber must be refired again. One german authority 
even refers to having the oven refired after every batch. 
His figures are : 

For first baking, 100 Kilo Bread requires 32 Kilo 
Wood. 

For second baking, 100 Kilo Bread requires 12 
Kilo Wood. 

For third baking, 100 Kilo Bread requires 8 Kilo 
Wood. 

For fourth baking, 100 Kilo Bread requires 7.5 Kilo 
Wood. 

The crown is built as low as possible and raised 
10 to 14 inches in center, sloping on both sides from 
4 to 6 inches, above the hearth or sole. Further, the 
hearth of the genuine Vienna Oven also slopes from 
back to front. The object of this is to keep the steam 
from coming out of the mouth or oven door. (See 
Steam.) 

The author of this book has had some of these 
old style Vienna Ovens under his supervision, which 
were fired with natural gas. Two or three large gas 
pipes are run into the oven chamber extending about 
18 inches into the oven, set at an angle towards the 
crown, with valves and air chamber on outside of the 
oven to the right of the oven door. When gas is turned 
on, long flames will stream along the crown of the 
oven chamber, diagonal towards the left rear wall 



Part 5 19 

where the damper is located. After being fired from 2 
to %y 2 hours steady, the arches should show a white, 
heat, and the hearth a bright red when gas is turned 
off. Being allowed to stand off for at least one hour, 
it is ready for baking. Steam being injected or water 
splashed in, these ovens bake especially nice milk or 
water rolls (hearth rolls.) After a few bakings, the 
gas is turned on again for from 15 to 30 minutes. 

The more popular style of direct fired oven, very 
efficient for general baking, bread, cake and pies has 
the furnace placed inside the baking chamber on one 
side of the door in front, the damper being on the op- 
posite side. After the fire is lit, the heat travels to the 
back of the chamber and then turns back to the flue to 
reach the chimney, or in more modern ovens, the heat 
chamber above the baking chamber. It is best to let 
oven rest awhile after damper is closed and fire cov- 
ered or drawn, to settle the heat. The advantage of 
this oven is, that you can cool it down and get up a 
flash heat again in short time, which is of special value 
where small batches of different kinds of baked stuff 
are wanted alternately, depending on one oven. 

The grate is set a few inches below the sole or 
hearth. Having no extra heat storage chamber, it is 
essential that the heat is allowed to linger longer in the 
oven, and a slow fire (or a larger fire banked) should 
be kept during the time there is no baking done. 

This style oven is built as a stationary brick oven 
or portable oven, the out side frame being metal, stand- 
ing on iron legs. 

*" INDIRECT OR FURNACE FIRED OVENS 
we call such ovens which have a furnace underneath 
the oven-chamber, fired from front, side or rear, the 
fire or heat traveling around and over the top of the 
baking chamber, adopted principally for Portable ovens 
or as in Shelf ovens, where stove pipes are run through 
the baking chamber from the stove or furnace under- 
neath. REEL and ROTARY also have a furnace be- 
low, but the heat strikes the baking chamber more 



20 Part 5 

directly, as the furnace is open on top or only partly 
arched over the top. 

REEL OVENS are used almost exclusively in 
Cracker bakeries, on account of the shelves or plates 
being so easily reached with the peel for rilling and 
emptying, but are also used in some large bread baker- 
ies for pan-bread. They are built on the principle 
of a Ferris Wheel. The baking blades are made of 
steel or sheet iron. 

ROTARY OVENS have only one baking surface 
revolving like a Merry-go-round. These ovens have a 
tile or soapstone hearth and are mostly used for pie 
baking. 

CONTINUOUS or HOT AIR CHAMBER 
OVENS are usually called Patent Brick Ovens and 
are the most popular for bread baking exclusively. 
The heat never strikes the baking chamber direct, being 
fired from the furnace below, either in front, side or 
back. The heat is accumulated and stored in chambers 
below and above the baking chamber, and no flame, 
smoke or dust can enter the same. The heat being 
stored, they are generally fired some hours before bak- 
ing is commenced, and can be used continuously. 
These ovens are preferred for baking bread and rolls 
exclusively on account of the heat being constant and 
uniform, but are not so practical for a general baking, 
including bread and cakes on account of the difference 
of heat required. When once the baking chamber is 
allowed to cool down, as needed for cakes it takes some 
time to get it hot enough again to bake bread. 

The baking chamber of the Continuous Ovens 
measures generally from 10 to 13 feet wide by 12 to 
14 feet deep inside measurement. Of late, however, 
these ovens are built in much larger sizes with uride 
mouth or tiuo doors. The hearth is from 14 to 22 or 
even 25 feet across, by 13 to 14 feet deep. Although 
these new features were looked at by the bakers very 
sceptical and considered in diametrical opposition to all 
theories and traditions of oven building, they have 



Part 5 21 

apparently given complete satisfaction so far. A great 
saving of fuel and labor, besides offering many con- 
veniences and better facilities for peeling and un- 
loading. 

HOT WATER OR STEAM PIPE OVENS are 
heated with a number of wrought iron pipes, located 
below and above the oven sole or drawplate. These 
pipes, are partly filled with water and hermetically 
sealed on both ends. The rear ends extend about a 
foot or less into the furnace which is usually at the 
rear of the oven. The furnace heat converts the water 
in the pipes into steam, and this steam being prevented 
from escaping, acquires a continually rising atmos- 
pheric pressure upon the water and a higher temper- 
ature is the result, which is transmitted from the pipes 
throughout the baking chamber. These pipes or 
tubes being first carefully tested as to their strength 
and flawless tightness, by exposing them to a consid- 
erable higher pressure than required for the baking 
heat, there is little danger of explosion. However, if 
in time any of the pipes should burst or swell, it is an 
easy matter to replace any single pipe with a new one, 
as they are not connected or dependent in any way on 
one another. The most popular Steam Pipe Ovens are 
the DRAWPLATE. The principle of these ovens 
which also accounts for the name, lies in the arrange- 
ment of the baking plates being removable from the 
oven chamber. The slower process of loading the oven 
with the peel, has led to the idea of building ovens 
with sliding plates, which can be withdrawn, loaded 
quickly, and running mechanically on wheels, pushed 
back into the oven. The objection to the extra space 
required, when plates are pulled out, has been greatly 
dispelled, with the construction of Double deckers, one 
on top of the other, practically taking only the space 
of a single decker, and reducing the cost of construc- 
tion as well as the cost for fuel and operating. 

TRAVELING or CHAIN OVENS have been in 
use in Europe for baking crackers and small sweet 



22 Part 5 

goods for some years, and in this country for Matzos. 
They are equipped with a steel wire netting or steel 
plates fastened to endless chains traveling through the 
baking chamber which can be from 30 to 60 feet long ; 
speed can be regulated, fast or slow. Attempts have 
been made lately to build this style oven for bread 
baking. The writer has had an opportunity to watch 
the baking process of the first oven of this kind built 
in America (in Montreal, Canada) and was very favor- 
ably impressed with the uniformity in baking, simplic- 
ity of mechanism and great reduction in oven help. 
The baking chamber in this oven is 50 feet long and 5 
feet wide. The firing is done from a small tunnel built 
under the center of the oven where two furnaces are 
located, one running towards the rear, the other to- 
wards the front of the oven. It requires comparative- 
ly a small amount of fuel considering the amount of 
bread turned out in a day's baking, from 8,000 to 12, 
000 loaves and its capacity is claimed to be far above 
that amount, being a continuous baker. 
FIRING. 
The proper firing of any bake oven depends on 
the construction of the flues and heat chambers, the 
kind of fuel and the draft of chimney, and differs 
greatly from firing a boiler or larger furnace. I have 
twice tried the experiment to put regular firemen in 
charge of firing the bake ovens. Both men claimed 
to be expert firemen ; one having fired on Railroad 
Locomotives, the other in a large power house. How- 
ever, both failed to make good ; they were so used to 
keeping on firing and poking and keeping up a lively 
fire, which we do not require for our Ovens. A well 
known baker remarked at a convention, "I am satisfied 
the fuel can be reduced twenty per cent or more, if it 
was handled with judgment, but it seems impossible 
to get laborers to use brains, they simply go on firing 
without using any judgment." Now, I never trust 
the firing of any oven to a cheap laborer, whether there 
is one oven or ten to be looked after. 



Part 5 33 

When starting a new fire with coal or coke in a 
cold oven, you will have less smoke and less loss 
of heat by kindling the wood in the front part of the 
grate, throwing a few shovels full of fuel in the back 
part of furnace, to raise its temperature first to the 
igniting point before spreading it over the new fire, 
and vou will not smother the flames. 

When burning BITUMINOUS or Soft Coal, 
which as stated before contains large amounts of vol- 
atile or gaseous matter, I recommend the so-called 
caking system for firing. This means when charging 
the fire with fresh coal, the cool is piled in the front 
part of the furnace as close as possible to the door and 
left there from 10 to 15 minutes. As this coal is get- 
ting heated, the volatile matter (hydrocarbons) are 
driven off as vapor or gas making the coal carbonized 
or coked, and they will give more heat and make less 
smoke when later pushed back and distributed evenly 
over the fire, besides, these escaping gases while pass- 
ing over the fire in the rear, yield a good percentage 
of heat (8,000 to 12,000 B. T. U.) Although soft coal 
is considered cheaper than hard coal or coke, it re- 
quires more care and judgment as they will produce 
soot and smoke, clogging up the flues and chimney and 
leave more ashes to be removed. The loss of heat 
from these causes is often as high as 50 per cent. 
(See fuel, page 11.) 

Burning ANTHRACITE or HARD COAL, a 
smaller fire is required, especially in Patent Ovens. 
Don't smother the fire with piling too much fresh coal 
on top of it, especially if wet. (see fuel.) The smaller 
the size of the coal, the more you will choke or chill the 
fire and obstruct or prevent combustion, besides burn- 
ing out the grate bars, (see page 9) Percentage of 
ashes varies from 8 to 24 per cent in hard coal. When 
coal is wet, the coking system mentioned above will be 
found of great advantage. Firing hard coal in Draw- 
plate Ovens, I prefer Chestnut and Egg mixed. For 
direct firing Furnace Ovens, Egg Coal is the best size. 



24 Part 5 

For Reel and Rotary Ovens, larger sizes are prefer- 
able ; Egg or Stove or both mixed ; but I prefer coke 
in either oven. 

COKE, as stated before (see fuel) is composed of 
about 89 per cent pure carbon, or plainly speaking, 
gives 89 per cent heat and only about 10 per cent ashes. 
Many bakers make the mistake when burning coke, to 
start the fire too slow. The coke being honeycombed 
and leaving so much space for air to pass through, 
you should fill the furnace considerable more then with 
coal, and also pull the damper wide open, until there 
are no more dark spots to be seen in the fire. The arch 
as well as the coke must show almost a bright light red 
heat, which should take from 40 to 50 min. Then close 
the damper, leaving about one inch opening for the 
escape of the gases. After, say two hours from time 
of firing, you will notice no more flame or just the least 
bit of a bluish tongue of flame ; then you close damper 
down tight, and the heat will last from 10 to 12 hours. 
Coke fires never need much shaking of grate or poking 
of fire. When once you have a solid fire, the most that 
may be required, is to pull damper two or three inches 
after several hours for 15 or 20 min. To get a good 
solid heat from coke, let first firing burn up brisk, then 
shake down or poke a little, to settle; then fire the 
second time which will be sufficient to last for a day's 
baking. 

The most important rule to get best results from 
any kind of fuel in a Patent or Hot Air Chamber Oven 
is, to let fire draw brisk first, then close damper half 
until top arch and sides show bright red clear back to 
flues. This is what produces storage heat, because so 
long as the fire draws and the dampers are open, the 
heat will pass through the chambers rushing for the 
chimney. I can demonstrate the value of solid heat in 
a good Patent Continuous baking brick Oven best, 
from our own report of our average Friday's Baking 
(for Saturday) which means about forty-six thousand 
loaves. Our ten continous baking ovens which have 



Part 5 25 

not been fired after ten o'clock Friday morning are 
almost continually used from one A. M. Friday to one 
A. M. Saturday, full 24 hours. No baking being done 
on Saturday, they stand idle, and instead of cooling off 
(with no fire in the furnace) the accumulated heat 
penetrates the oven chamber, and by Saturday we even 
open front oven door, (baking chamber) and smoke 
damper for several hours, to let the heat out and start 
baking Sunday morning with practically the heat left 
over from previous Friday. The fire started Saturday 
night will not have full effect until Sunday noon or at 
least 6-8 hours after being started. Just get the arch 
to white heat once in twenty-four hours, and you can 
bake bread continually. However, if such ovens must 
be cooled down for cakes, it is a matter of many hours 
to get the solid heat back again. 

Ovens used exclusively for Hearth Bread must 
have a good bottom heat to give the loaves a good 
spring, otherwise they run flat. Drawing so much heat 
continuously, a larger fire must necessarilly be kept in 
the furnace, but little or no extra draft is required, 
the object being to keep the heat lingering under the 
Oven chamber as much as possible. An occasional 
rest is of great benefit and the Thermometer or Pyro- 
meter will go up 20 to 30 degrees in a short time. 

IF MIXED BAKING, Bread, Cakes and Pies are 
to be done in one oven, the DIRECT FIRED brick or 
portable oven is very popular. As already explained 
(see ovens) grate is set a few inches below level of 
oven sole. I advise a banked fire to be kept all during 
time there is no baking, and giving it before baking is 
commenced a slow draft to allow the product of com- 
bustion, seen in long pale tongues, to spread and 
linger along the crown or top of oven chamber. There 
are several styles of modern PORTABLE OVENS 
with furnace below the baking chamber which turn out 
a large amount of well baked goods. It is to be 
specially recommended, to start a moderate fire at long 
as possible before baking time to get a more uniform, 



26 



Part 5 



steady heat. Natural gas being used as fuel, I have 
always found it a fuel saver and heat preserver to pile 
some fire brick loosely in the fire box or furnace for the 
gas flames to pass around them. 





Judging Heat by Color. 




Temperature 
Fahrenheit. 


COLOR. 


Temperature 
Fahrenheit. 


COLOR. 


900° 


Red (dull) 


1900° 


Orange 


1200 


Red (dark) 


2100 


Yellow 


1400 


Red (cherry) 


2300 


White 


1600 


Red (bright) 


Over 2500 


White (dazzling) 



Melting Point of Different Metals. 



Name. 


Degree F. 


Name. 


Degree F. 


Tin 


446° 


Copper 


1996° 


Lead 


608 


Glass 


2377 


Zinc 


680 


Iron (cast) 


2450 


Aluminum 


1400 


Steel 


2500 


Bronze 


1692 


Gold (pure) 


2590 


Silver 


1873 


Iron (wrought) 


2912 


Brass 


1900 


Platinum 


3080 



Part 5 27 

DRAFT. 

Draft is a current of air, and as we have learned 
from chapter on combustion, air is the life of fire, and 
the briskness of the fire depends entirely on the proper 
amount of air supplied. Therefore, it is most impor- 
tant to have proper facilities to increase or decrease 
this current of air (Draft.) To control or regulate 
the draft, we need the draft door on the ash-pit (below 
the fire) and the damper in flues or chimney (above 
the fire.) They work in conjunction with each other. 
Either one worked alone will be a waste of heat or 
fuel. The draft door should be so arranged that it 
can be kept wide open, half open or nearly closed, or 
it must be perforated and supplied with a slide to reg- 
ulate the air supply. The size of furnace depends on 
kind of fuel used. Soft coal being lighter than hard 
coal, requires more area for the same amount (by 
weight) as hard coal. When burning coke, the grate 
can be set a few inches below the dead plate in front 
and the bridge in back of the grate, a larger amount 
of coke being fired at one time, than coal. This is 
especially to be considered in direct or inside fired 
ovens. The grates, most always made of cast iron, 
do not only hold the fuel, but also admit the air, and 
for that reason must have open spaces between the 
supports. At least half the grate surface must be air 
space, the other half (the bars) serving to hold the 
fuel. There are different styles of grates used by 
different Oven Manufacturers. The single bar grate 
is very popular; about 2^4 to 3 feet in length. The 
thickness of the lugs on both ends determine the 
width of the open spaces of the grate. These bars are 
more or less sloping (thinner) on the bottom, which 
gives a better air supply. Another style used more 
for very small coal (as in boilers), is the Herringbone. 

SHAKING GRATES are preferred by many 
bakers and used in most all portable ovens, and are 
especially an advantage where the square fire-box or 
round pot is set below the furnace proper. Another 



28 Part 5 

great advantage of a shaking grate, is because the 
furnace door can be kept closed while raking the fire, 
and no smoke or ashes will blow into the shop. The 
inrush of cold air over the fire through the open fur- 
nace door (the damper always being opened when 
shaking fires) is also avoided, which means preventing 
a loss of heat. 

The furnace door should also be perforated and 
have a slide, especially when coke or soft coal, rich 
in carbohydrates are burned, as in this way, some air 
can be admitted over the top of the fire to mix with 
the gases which linger on top of fire, causing com- 
bustion of same. The admission of steam or water 
under the grate or furnace does not produce more 
heat, as some bakers imagine. It is only of benefit 
when coal are used, which stick to the grate bars or 
clinker badly ; the steam coming from below will 
prevent this to some extent, keep the grate clear and 
also keep it from burning or melting. A better dis- 
tribution of air and more complete combustion is the 
result, which also means indirectly, a saving of fuel. 
But, care must be taken not to admit too much steam, 
and I recommend the safer method of keeping a 
basin of water in the ash-pit, or better still, to have 
the bottom ash-pit cemented, and a few inches lower 
than the floor, keeping a small pool of water in same. 
Glowing pieces of fuel dropping through the grate 
will create sufficient steam for this purpose. 

CHIMNEY AND FLUES. 
The chimney answers two purposes ; (1) to create 
a natural draft for the fire; (2) to carry off the ob- 
noxious gases of combustion and the smoke. The 
area and height of a chimney and the position of its 
top outlet to the surrounding buildings, has an im- 
portant bearing when erecting a chimney. Gases, 
hot air and smoke always ascend in a spiral column, 
which means, for instance, that a ten by ten-inch 
square chimney flue is no better or its practical work- 



Part 5 29 

ing area no more extensive than a ten-inch round 
flue. There is also less friction in a round chimney 
flue than in a square one, because the spiral ascent of 
the draft moves more easily. The efficiency of the 
chimney (flue) depends on volume of passage due 
to area (size of flue) and velocity due to height of 
chimney. Therefore, the suction or speed alone do 
not make perfect draft; there must also be sufficient 
room to carry off the smoke. The chimney top should 
reach above the surrounding buildings if possible, 
as wind currents will rebound or be checked by walls 
or roofs in their way, and will force the air down into 
the chimney. It is also well known that there is quite 
a difference in draft of a chimney in summer or hot 
days and that produced in winter or cold days. On 
damp and murky days the draft is especially poor, and 
it is more difficult to get sufficient heat out of the fuel. 

The outside air passing over the top of chimney, 
say ranges between 40 and 85 degrees on an average, 
while the hot gases passing through the chimney 
average from 400 to 450 degrees. Bulk for bulk, the 
outside air has about twice the weight of the hot gases. 
In localities high above the sea level, where air is 
rarified or thinner, a larger volume of same must be 
supplied to get sufficient oxygen for combustion. 

The wind or air currents passing over the chim- 
ney, carry off the gases or hot air and smoke as they 
come from the furnace, also create a suction or draft. 
With a high wind blowing, the fuel will burn away 
more or less briskly, even if the draft door (ash-pit) 
is closed as long as damper in chimney or flue is wide 
or even only partly open. The inside area of a chim- 
ney should never be less than 9 or 10 inches if round, 
or 8 x 12 rectangular, or 10 x 10 square, or always be 
a little larger than the end of stove pipe or flue where 
it leads into the chimney. Never have the end of 
stove-pipe, bricks or casing of flue, etc., extend beyond 
the inside surface or wall of chimney, neither allow 
any crevices or leaks, as the least obstruction prevents 



30 Part 5 

the free passage of gas and smoke. The inside walls 
of chimney should be as smooth as possible. Some 
masons are very careless in this respect. The inside 
finish of a chimney is certainly of more importance 
than the outside, and every baker should watch the 
erection of any new chimney very carefully. Every 
oven should have its own chimney flue if possible, and 
no other flues or stove-pipes running into it. For a 
Two Oven chimney, it is best to allow a double area, 
and have a thin partition running up through the 
center. Sharp bends or offsets in the chimney will 
also reduce the area and choke the draft. If there is 
a soot pocket in the chimney below the point where 
the smoke-pipe or oven flue runs into the chimney, 
the same should never be deeper than one or two feet, 
and the slide or door of same must be kept closed 
perfectly tight. 

DAMPERS are checks or valves in or above the 
chimney, and control the draft. On Continuous Bak- 
ing and Portable Ovens, dampers usually have the 
shape of a slide, to be operated from front of oven, 
by a rod. On Draw-plate and Reel Ovens, the damp- 
ers generally consist of a drop door or lid, fitted over 
top of chimney, and are operated by a chain. The 
reason for the latter arrangement is, on Reel Ovens, 
especially used for crackers, there must be a constant 
flash heat and a quick draft and frequent manipulation 
of damper is necessary. On Draw-plate Ovens, the 
heating surface (see ovens) is so small, that the fire 
must be drawing nearly all the time, more or less, 
and the drop door on top of chimney is more efficient 
for the purpose. I would not recommend to have the 
inside area of chimney reduced toward the top, es- 
pecially when solid fuel is burned, coal or coke. Some 
bakers think by running the brick chimney only half 
way the required length, and putting a pipe on top, 
they save money. But alas, they have more annoy- 
ance from smoke or poor draft, and do not get the 
full heat value out of the fuel. Theoretically, anthra- 






Part 5 31 

cite or hard coal requires more draft than soft coal, 
but on account of the latter having a greater propor- 
tion of gaseous products of combustion, the flue area 
must be larger for burning soft coal than for anthra- 
cite. The height of chimney does not matter materi- 
ally, but the difference in area of the flue required may 
be as high as 30 per cent, or a flue 8 x 12, good for 
hard coal fire, may have to be increased to 10 x 12 
for soft coal. So, when changing from one coal to 
another, it is often well worth looking up the available 
chimney area. Coke requires a good draft, but burn- 
ing easily without smoke, the area of chimney can be 
limited without danger to draft. 

To clean out flues and chimney, I throw salt on the fire 
and open damper. Amount of salt depends upon area to be 
cleaned. The sulphurous gases eat the suds in a very short 
time. I use rock sa ^> f rom three to six pounds. 
STEAM. 

A certain amount of steam or moisture is required 
for the heat of the baking chamber during baking. 
The amount, of course, varies widely, and every baker 
knows that especially for Rye and Vienna Bread and 
Rolls, in fact anything baked direct on the Oven-hearth, 
a larger amount of steam is necessary, and the supply 
of steam must be replenished ; therefore, it is essen- 
tial that no steam can escape. In inside fired ovens, 
the direct fire leaves more or less moisture in the oven 
chamber. In smaller bakeries, with only one oven, 
perhaps a portable one, with no live steam supply, you 
may produce sufficient moisture by placing a pan of 
water near the fire-place and get it boiling. However, 
small boilers of sufficient capacity can now be bought 
so reasonable, that it will be a paying investment even 
for the small baker, as he can do all his cooking, pie 
filling, icings, mush, etc., in shorter time, and have a 
liberal supply of steam for proof boxes. Most Oven 
Builders also make it a point to supply steam or hot 
water boilers to their ovens on request. However, I 
prefer an independent boiler as a safer proposition, 



32 Part 5 

as you can raise or lower your steam supply or pres- 
sure at any time with very little fuel and in a few min- 
utes. For larger bakeries, of course, more steam and 
larger boilers are required. However, the pressure 
should not be over 30 lbs., and always carry plentv 
water in the boiler, at least 2 to 2^ gauges, to keep the 
steam moist. Dry steam or too much steam in oven 
is worse than not any at all. Some bakers think steam 
is steam, and always alike, and I have found it difficult 
to convince some of the old oven men that they can 
use too much steam. Of course, most ovens have a 
steam damper in the rear in the baking chamber, by 
which you can let surplus of flash heat and steam 
escape. 

Steam for Bakeovens is best at a pressure from 
15 to 30 pounds and the boiler should never be allowed 
to be less than half to two thirds full of water, indi- 
cated on the water gauge. While drawing the steam 
from boiler, you will notice the gauge (indicating the 
pressure) drop rapidly. Therefore, you must keep 
up a good fire. For this reason you may have 30 
pounds pressure at the start; it will then be easier to 
keep it from going below 15 pounds, which is called 
one Atmospheric pressure. 

Steam is like gas, expanding through application 
of heat. The temperature of steam increases with the 
amount of pressure (indicated on the gauge) as shown 
in the following table: 
Pound Pressure Temp, of Steam 

212 degrees F. 

5 227 degrees F. 

10 239 degrees F. 

20 259 degrees F. 

30 274 degrees F. 

40 286 degrees F. 

50 300 degrees F. 

At about 320 degrees, F. steam is thoroughly 
"dry" and will just do the opposite to your bread, from 
what it is expected to do. 



Part 5 33 

It will cause it to be "blind," "shrink" the loaves 
or it will even "char" the crust. Now as the tempera- 
ture of the Oven is about 450 degr. F., and on account 
of steam expanding with increase of heat, the oven 
will be full of superheated steam, when forcing it in 
quickly. "Through steam" or superheated is prac- 
tically invisible. What you see issuing from the spout 
of a closed tea-kettle, is condensed steam and visible as 
vapor. The lower temperature of surrounding at- 
mosphere chills or condenses the steam and naturally 
in cold weather you can see steam much plainer than 
in warm weather. You can notice that on your own 
breath. The only true steam issuing from the spout 
of a kettle or any other closed receptacle, (valve of a 
steam boiler, etc.) is contained only in the small space 
immediately in front or on top of the point, where it 
issues into the atmosphere. You can notice this empty 
space very plain wherever steam escapes. 

Steam will always look for an outlet but does 
not descend below the highest point of exit, for in- 
stance, the oven door. For this reason, Vienna or Rye 
Bread Ovens are built sloping from back to front and 
the front door provided with a tin slide which can be 
lowered while peeling in Vienna or Rye Bread, to pre- 
vent the steam from escaping through oven door. 

A strong kettle or pot with tight cover and spout 
is preferable. A very simple arrangement for any oven 
is to run a one inch pipe over the fireplace or if oven 
is fired from below, run pipe along the inside wall, of 
oven chamber; the pipe is connected with the cold 
water and is perforated. The pipe takes on about the 
same heat as the oven chamber and when you turn on 
a little cold water it will instantly turn into steam and 
spread through the oven. 

OVEN RECORDS. 

Every baker, no matter how small or how large 
his business should keep occasionally a record of a 
whole day's baking of one or more ovens, marking 
down the heat variations, fuel consumed, amount of 



34 



Part 5 



baking turned out, time oven is fired, etc. I refer to 
my own Oven Record Cards, samples of which I re- 
produce herewith (filled out). With these cards I 
was able to cut down the fuel gradually to less than 
one half the amount previously used. My fireman 
knows the character of every one of our ten ovens 
exactly, how much fuel every one requires, how often 
to fire, when to close dampers, etc., of course in our 
bakery the heat recording is much simplified as our 
Ovens are equipped with Electric Pyrometers, all oper- 
ated from one switch-board and all recording the exact 
heat of each oven. I find that 450 degrees F. is the 
proper heat to start Bread Baking. I give here a 
record of the variations indicated on the "dial" of the 
switch-board for each oven, at different hours during 
one day's baking. 





Re< 


:ord of Heat Variations. 






Fuel 


No. Oven 


TIME AND DEGREES OF HEAT. 


11 P.M. 


2 A.M. 
450 


6 A.M. 


10A.M. 


4P.M. 


8 P.M. 


Coke 


1. 


435 


430 


420 


430 


435 


Coke 


2.X 


440 


445 


395 


390 


405 


435 


Coal 


3. 


450 


460 


430 


415 


430 


440 


Coal 


4.X 


435 


450 


400 


385 


405 


425 


Coke 


5.X 


440 


455 


395 


395 


390 


430 


Coal 


6.X 


450 


460 


405 


395 


420 


415 


Coal 


7. X 


445 


455 


400 


390 


395 


420 


Coke 


8. 


450 


450 


440 


435 


430 


445 




9. 


Oven 


in Re 


pair 








Coal 


10. 


440 


440 


445 


445 


430 


435 



Ovens marked X are used for Hearth bread, which 
accounts for the drop in temperature. Firing started 
at 11 P. M., Baking started at about 3 A. M. 



Part 5 



35 



OVEN REPORT. 

BRAUNS " PRACTICAL" SYSTEM^- 

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36 



Part 5 



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OVEN REPORT. 



BRAUN'S "PRACTiCAL" SYSTEM. 



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LIBRARY OF CONGRESS 




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